We used Easy Grammar in grades 4-5. I'll probably pull out one of the higher level ones when my son is in high school, to cover the more advanced concepts. The one linked above is "Easy Grammar Plus" - no grade level in the title. It's intended for anyone grade 7 and up. My experience with EG is that the higher level programs still cover the basics, just more quickly.

It's not a "fun hands-on" kind of program, but it really is logical and "easy".

I second the "Easy Grammar" series. It only takes about 15 min/day and while it isn't colorful and full of games--that is actually a selling point here. My dd liked that it was no nonsense, get this DONE sort of thing. We have also used the MCT series (mentioned above)--and while I thought it was more of a pleasure, she didn't. She felt the stories were a bit too abstract and I repeatedly needed to help her understand the point.